On Saturday November 12, 2016, AVO received reports from local residents of an avalanche feature on the northeast flank of Frosty Volcano, located 8 mi (13 km) southwest of Cold Bay. Analysis of photographs received by AVO show that a small portion of the summit bedrock spire of Frosty collapsed and formed a prominent linear avalanche track of rock, ice, and snow that was visible from Cold Bay. The precise timing of the avalanche is not currently known, but based on the photographs it must have occurred prior to 10:35 am AKST on Friday November 11. The collapse is not due to volcanic activity and was likely the result of the failure of unstable, altered and weakened rock that makes up the summit of the volcano. Similar rock, ice, and snow avalanches have occurred previously at Frosty, most recently in 2001. No other signs of unrest have been detected at Frosty and the volcano has had no confirmed historical eruptions. Eruptive activity within the past several thousand years has been documented by AVO in preliminary studies of the volcano.

Occasional avalanches of rock, ice and snow may occur due to the altered and weakened nature of the rock that forms the summit spire, along with the steep summit topography. Such avalanches can be triggered by freeze-thaw processes, strong regional earthquakes, heavy rainfall, or possibly snowfall. At present, there is no local seismic network on Frosty Volcano, although strong seismicity, should it occur, would likely be detected by a nearby network on Dutton Volcano approximately 24 mi (38 km) to the east. AVO does not interpret the avalanche as a sign of precursory volcanic unrest and it remains possible for additional avalanches to occur from the summit. Should additional avalanches occur, these would likely be due to the unstable nature of the rock at the summit and not an increase in volcanic unrest.

The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.